Many different types of data storage systems exist and are being used to store data cartridges at known locations and to retrieve desired data cartridges so that data may be written to or read from the data cartridges. Such data storage systems are often referred to as "jukebox" data storage systems, particulary if they can accommodate a large number of individual data cartridges.
A typical jukebox data storage system may include one or more different types of cartridge receiving devices for holding the various data cartridges. For example, one type of cartridge receiving device may comprise a cartridge storage rack or "magazine" while another type of cartridge receiving device may comprise a cartridge read/write device. The cartridge storage racks or magazines serve to provide storage locations for the data cartridges and are commonly arranged so that they form one or more vertical stacks, although other configurations are possible. The cartridge read/write device may be located at any convenient location within the data storage system.
The data storage system may also be provided with a cartridge handling system for transporting the data cartridges between the various cartridge receiving devices, e.g., between the cartridge storage racks and the cartridge read/write devices. A typical cartridge handling system may include a cartridge engaging assembly or "picker" for engaging the various data cartridges contained in the cartridge receiving devices, as well as a positioning device for moving the cartridge engaging assembly among the various cartridge receiving devices.
Jukebox data storage systems of the type described above are usually connected to a host computer system (not shown) which may access or store data on the data cartridges. For example, if the host computer system issues a request for data contained on a particular data cartridge, a control system associated with the data storage system actuates the positioning system to move the cartridge engaging assembly or picker along the cartridge storage racks until the cartridge engaging assembly is positioned adjacent the desired data cartridge. The cartridge engaging assembly may then remove the data cartridge from the cartridge storage rack and carry it to the cartridge read/write device. Once properly positioned adjacent the cartridge read/write device, the cartridge engaging assembly may insert the selected data cartridge into the cartridge read/write device so that the host computer may thereafter read data from or write data to the data cartridge. After the read/write operation is complete, the cartridge engaging assembly may remove the data cartridge from the cartridge read/write device and return it to the appropriate location in the cartridge storage rack.
It is often necessary or desirable for a system operator to periodically access one or more of the data cartridges contained within such a jukebox data storage system. For example, it may be necessary for the system operator to remove certain of the data cartridges from time to time if they become filled with data that is to be archived at another location. The system operator may then replace the filled data cartridges with blank data cartridges. In another situation, the system operator may desire to remove one or more of the data cartridges and replace it or them with a substitute data cartridge or cartridges containing different data.
In order to accommodate the foregoing needs, many jukebox data storage systems are provided with an access panel to allow the system operator to access to the data cartridges stored within the data storage system. While such an arrangement is usually effective from a functional standpoint, it is usually difficult and cumbersome to implement in practice. For example, since the access panel needs to be removed in order to access the data cartridges, the data storage system must be temporarily shut-down or suspended in order to prevent the cartridge handling system from interfering with the system operator's access to the cartridges and to prevent injury to the system operator should the cartridge engaging assembly move while the system operator's hand is inside the data storage system. Another difficulty is that it is often difficult for the system operator to locate the particular data cartridges that are to be replaced. Still another disadvantage is that once the access panel has been replaced, it is necessary for the data storage system to re-inventory all the data storage cartridges contained therein. Such re-inventory processes are time consuming and difficult to justify, particularly if only one cartridge has been replaced. Nevertheless, the data storage system must re-inventory the data cartridges before the data storage system can be returned to service.
Partly in an effort to solve some of the problems associated with the foregoing type of data cartridge exchange system, a data storage system has been developed that includes an extendable drawer that can be pulled open to allow a system operator to access the data cartridges stored in the data storage system. An example of such a system is shown and described in U.S. patent application Ser. No. 09/179,793 filed on Oct. 27, 1998 and entitled "Mail Slot Data Cartridge Exchange System For Use With A Data Storage System," which is incorporated herein by reference for all that it discloses. Such an extendable drawer is useful in that it allows a system operator to access a data cartridge without the need to remove a separate access panel. Consequently, this drawer type of data cartridge exchange system eliminates the need to temporarily suspend the operation of the data storage system while the system operator is accessing the data cartridges.
Unfortunately, the drawer type of data cartridge exchange system is not without its disadvantages. For example, the drawer represents the addition of additional structure and components that will generally add to the overall cost and complexity of the data storage system. Such increased cost can be a disadvantage, particularly for smaller jukebox data storage systems capable of storing only a handful of individual data cartridges.